Mailgun SMTP Settings
Sinch-owned sending service with per-domain SMTP logins and separate US and EU regions.
Search for your email provider
Outgoing mail (SMTP)
SMTP server
smtp.mailgun.org
Port. STARTTLS
587
Port. SSL/TLS
465
Security
STARTTLS on 587/2525/25 or SSL/TLS on 465.
Incoming mail (IMAP)
IMAP
Not supported. This is a send-only service.
Incoming mail (POP3)
POP3
Not supported by this provider.
Sending limits & login
Daily send limit
Set by your Mailgun plan.
Authentication
Authenticate with the SMTP username (postmaster@your-domain) and the SMTP password from your domain's settings.
App password
Find or reset the SMTP password under Sending > Domain settings > SMTP credentials.
Mailgun is a send-only relay: there is no IMAP or POP inbox. EU-region domains use smtp.eu.mailgun.org.
Sending cold email? EmailChaser manages inboxes, warmup and deliverability for you.
Try EmailChaser freeFind the SMTP, IMAP and POP3 server settings for any email provider. Free, with no signup, every field copies with one click.
Mailgun SMTP, IMAP and POP3 settings
Mailgun is a developer-focused sending service, now part of Sinch. Its SMTP logins are created per domain rather than per account, so the username is a full address such as postmaster@yourdomain.com and each domain has its own password. Mailgun also splits its infrastructure in two: a domain created in the EU region must send through smtp.eu.mailgun.org, not the US host.
Mailgun is a send-only relay, so there's no IMAP or POP3 inbox. You only configure the SMTP server above. Use the tool to copy each value into your app or script.
Checked against Mailgun's own documentation: documentation.mailgun.com. Ports and limits change, so check there too if something will not connect.
Mailgun settings at a glance
One card with every server and port on it. Right click to save it, or share the page and this is the preview people see.
What to enter as your Mailgun username and password
Wrong credentials, not a wrong port, are the usual reason a Mailgun connection fails. These are the exact values to type.
The full SMTP login for that specific domain, for example postmaster@yourdomain.com
The SMTP password for that domain, from the SMTP Credentials tab in Domain Settings. Your Mailgun control panel password will not work.
Get your smtp passwordHow to set up Mailgun in a mail client
The exact path through Mailgun's own settings, in order.
- 1
Add your sending domain and pick a region
In the control panel go to Sending, then Domains, then Add New Domain, and choose US or EU. The region is fixed at creation and decides which SMTP host you use.
- 2
Publish the DNS records Mailgun shows you
Add the TXT records for SPF and DKIM, plus the CNAME for tracking, to your domain's DNS, then let Mailgun verify them.
- 3
Get that domain's SMTP credentials
Go to Sending, then Domain Settings, select the domain, and open the SMTP Credentials tab. Credentials are managed per domain there; a reset shows the new password at the moment it is generated, so save it straight away.
- 4
Configure the client
Host smtp.mailgun.org for US domains or smtp.eu.mailgun.org for EU domains, port 587 with STARTTLS. Ports 25 and 2525 also work and port 465 uses implicit TLS.
- 5
Add Authorized Recipients if you are on the free plan
Free accounts with no card on file, and sandbox domains, deliver only to addresses added under Authorized Recipients, up to 5 of them.
What Mailgun looks like filled in
Every mail client asks for the same handful of fields. Here they are with Mailgun's values already in place.
Account settings: Mailgun
Server
smtp.mailgun.orgPort
587Encryption
STARTTLSAuthentication
RequiredUsername
The full SMTP login for that specific domain, for example postmaster@yourdomain.comPassword
The SMTP password for that domain, from the SMTP Credentials tab in Domain Settings. Your Mailgun control panel password will not work.IMAP / POP3
Not applicable. Mailgun sends only, so there is no inbox to configure.An illustration of the fields, not a screenshot of any one app. Field names differ slightly between Outlook, Apple Mail and Thunderbird; the values do not.
Mailgun SMTP settings in Thunderbird
The outgoing server dialog with Mailgun's details entered. Outlook and Apple Mail ask for the same four things under slightly different names.
Which port should you use for Mailgun?
STARTTLS on 587/2525/25 or SSL/TLS on 465.
STARTTLS
Starts as a plain connection, then upgrades to an encrypted one. The modern standard for sending.
SSL/TLS
Encrypted from the first byte. Widely supported and a good choice when 587 is blocked.
Plain SMTP
Meant for server-to-server relay. Home networks and cloud hosts block it, so do not use it to send from a client.
Why your Mailgun connection is failing
The failures people actually hit with Mailgun, and what fixes each one.
EU domains authenticate only against smtp.eu.mailgun.org. The US host smtp.mailgun.org rejects the same username and password.
Mailgun SMTP logins are issued per domain, not per account. Open Sending, then Domain Settings, select the other domain, and use its own SMTP Credentials tab.
Sandbox domains, and free accounts with no card on file, deliver only to Authorized Recipients and that list is capped at 5 addresses. Add and verify a real domain and a payment method.
Mailgun's own relay documentation says you can use SMTP Credentials but not your Control Panel password. Reset the domain's SMTP password to generate a usable one.
Mailgun caps a message at 25 MB in total, and that is measured on the uncompressed body. Host anything larger and send a link instead.
Mailgun sending limits
Paid plans are metered by monthly volume (10,000 on Basic, 50,000 on Foundation, 100,000 on Scale) rather than a daily cap.
Per day
100 emails a day on the free plan
Recipients per message
1,000 recipients per batch send
Max attachment
25 MB total message size including attachments
Mailgun servers by region and plan
Mailgun does not use one set of hostnames everywhere. Match the row to your account.
| Region or plan | SMTP | IMAP | POP3 |
|---|---|---|---|
| US | smtp.mailgun.org | Not applicable | Not applicable |
| EU | smtp.eu.mailgun.org | Not applicable | Not applicable |
Mailgun quirks by mail client
Apple Mail
Enter the full address form of the login, such as postmaster@yourdomain.com, since Mailgun's own guidance for standard email clients is to use a full address as the SMTP login.
Sending cold email through Mailgun
Set by your Mailgun plan. Authenticate with the SMTP username (postmaster@your-domain) and the SMTP password from your domain's settings.
Those caps make single-mailbox sending fine for personal mail but a poor fit for cold outreach at volume. Emailchaser spreads sending across warmed inboxes and manages deliverability, so you can scale without burning Mailgun accounts.
Other smtp sending services
Setting up more than one mailbox? These sit in the same category as Mailgun.
Common questions about Mailgun SMTP settings
What are Mailgun's SMTP settings?
Mailgun's outgoing (SMTP) server is smtp.mailgun.org. Use port 587 (STARTTLS) or 465 (SSL/TLS). STARTTLS on 587/2525/25 or SSL/TLS on 465. Sign in with the SMTP credentials Mailgun issues you, not a mailbox address and password.
What is Mailgun's IMAP or POP3 server?
Mailgun is a send-only service, so it has no IMAP or POP3 inbox. You configure it as an outgoing SMTP server only.
Which port should I use for Mailgun?
Use port 587 with STARTTLS wherever it's offered, it's the modern standard for authenticated sending. Port 465 with SSL/TLS is a solid alternative. Avoid port 25, which most networks block for client sending. Mailgun's recommended value is above.
Why won't my Mailgun SMTP connection work?
Check authentication first: Authenticate with the SMTP username (postmaster@your-domain) and the SMTP password from your domain's settings. Find or reset the SMTP password under Sending > Domain settings > SMTP credentials. Then confirm the host, port and security method match exactly, a 587/SSL or 465/STARTTLS mismatch will fail to connect.
Can I send bulk or cold email through Mailgun?
Not at scale. Set by your Mailgun plan. Providers throttle bursts to fight spam, so pushing cold email through one mailbox hits limits and wrecks deliverability. High-volume outreach belongs on dedicated infrastructure that spreads sending across warmed inboxes, which is what Emailchaser does.
Why can I only send to a few addresses on a new Mailgun account?
Sandbox domains and free accounts without a card on file are restricted to Authorized Recipients, a list of at most 5 addresses that each have to confirm by email. It exists to stop new accounts being used for spam. Adding a verified custom domain and billing details removes the restriction.
Do I get one SMTP password for my whole Mailgun account?
No. Every domain you add has its own SMTP username and password, managed on the SMTP Credentials tab for that domain. If you move sending to a second domain you have to create or reset credentials there too. This also means revoking one domain's password does not affect the others.
What changes if my domain is in the EU region?
The whole set of endpoints changes. Outgoing SMTP becomes smtp.eu.mailgun.org, the API base becomes https://api.eu.mailgun.net/, inbound routes use mxa.eu.mailgun.org and mxb.eu.mailgun.org, and tracking runs through eu.mailgun.org. Message data stays inside the region it was processed in.
Ready to 10x your pipeline?
Send your first cold email campaign today.
Start my free trialAddress: 151 Calle de San Francisco San Juan, Puerto Rico
Email: support@emailchaser.com
Product
Cold Email SoftwareAutopilotEmail FinderCampaignsSales CRMLead FinderEmail AccountsEmail WarmupEmail VerifierCold Email APIMCP ServerAPI documentationWho it's for
FreelancersFoundersSales teamsMarketing agenciesRecruitment agenciesLead generation agenciesComparisons
Best cold email softwareInstantly alternativesSmartlead alternativesInstantly vs EmailchaserSmartlead vs EmailchaserHunter vs EmailchaserFree tools
All free toolsBulk Email VerifierDeliverability TestEmail Header AnalyzerSMTP Settings FinderCold Email TemplatesBoolean Search BuilderAudience Size CalculatorName SplitterCompany Email FormatSpam Word CheckerInternational
Cold email (ES)Cold email (FR)Cold email (DE)Cold email (IT)Cold email (PT)Verifica email (IT)© Copyright 2026 Emailchaser